godan verb (-ru), transitive verb
overestimate; overrate; think too highly of
Used when someone rates a person's ability, character, or potential higher than it really is. Often used reflexively or about others.
彼は私を買いかぶりすぎだ。
He overestimates me too much.
自分の力を買いかぶってはいけない。
You must not overrate your own ability.
Standard kanji-kana mixed spelling; the verb is commonly written with the first kanji and the rest in kana.
Full kanji spelling; less common but still seen.
過大評価 is a more formal noun/する-verb meaning 'overestimation' and can be used for things as well as people, while 買いかぶる is a colloquial verb used mainly for people.
Compound of 買い (stem of 買う 'to buy') + かぶる (被る 'to put on one's head; to take on'), literally 'to buy and put on', implying taking on a higher value than warranted.